usb: storage: ene_ub6250: remove unused variable

The variable Newblk was only being assigned some value but was never
used after that.

Signed-off-by: Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>